LG MB-387W Service Manual

LG MB-387W Manual

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  • LG MB-387W | Service Manual - Page 1
    Website: http://biz.lgservice.com MICROWAVE OVEN SERVICE MANUAL MODEL: MB-387W CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL. P/NO : 3828W5S2280 June, 2002 Printed in Korea
  • LG MB-387W | Service Manual - Page 2
    Before turning on microwave power for any service test or inspection within the microwave generating compartments, check the magnetron, wave guide or transmission line by procedures described in this manual before the oven is released to the owner. E) A microwave leakage check to verify compliance
  • LG MB-387W | Service Manual - Page 3
    2-1 INSTALLATIONS 3-1 OPERATING INSTRUCTIONS 4-1 FEATURES 4-1 CONTROL PANEL 4-1 OPERATING SEQUENCE 4-2 SCHEMATIC DIAGRAM 4-3 CIRCUIT DESCRIPTION 4-4 SERVICE INFORMATION 5-1 TOOLS AND MEASURING INSTRUMENTS 5-1 MICROWAVE LEAKAGE TEST 5-1 MEASUREMENT OF MICROWAVE POWER OUTPUT 5-3 DISASSEMBLY
  • LG MB-387W | Service Manual - Page 4
    MB-387W 230 Volts AC 50 Hz Single phase, 3 wire grounded Microwave 1,200W Gril 1,000W Combination 2,150W 800 Watts full microwave Location Control panel side Accessories Owner's manual Glass turntable Roller Rest Grill rack This microwave oven is designed for household use only
  • LG MB-387W | Service Manual - Page 5
    into an open waveguide or antenna while the device is energized. • Proper operation of the microwave oven requires that the magnetron be assembled to the waveguide and cavity. Never operate the magnetron FIN MAGNETRON CHASSIS GROUND MAGNETRON THE OVEN IS TO BE SERVICED ONLY BY PROPERLY QUALIFIED
  • LG MB-387W | Service Manual - Page 6
    door or dents inside the cavity or on the exterior. EARTHING INSTRUCTIONS This microwave oven is designed to be used in a fully earthed condition . It is imperative, therefore, to make sure it is properly earthed before servicing
  • LG MB-387W | Service Manual - Page 7
    OPERATING INSTRUCTIONS FEATURES Oven Front Plate Window Door Screen Door Seal Control Panel Grill Rack CONTROL PANEL 480W 320W 640W 160W 1 800W 2 3 7 4 5 8 6 9 Safety Door Lock System Turntable
  • LG MB-387W | Service Manual - Page 8
    currently in use. The display will either return to the last item entered or to the clock. 3. QUICK START Stop Start 4. MICROWAVE COOKING Stop Micro Time Start 5. GRILL COOKING Stop Grill Time Start 6. COMBI COOKING Stop Combi Time Start 7. AUTO WEIGHT DEFROST Stop Desired
  • LG MB-387W | Service Manual - Page 9
    SCHEMATIC DIAGRAM 4-3
  • LG MB-387W | Service Manual - Page 10
    micom controller. • Power input is supplied to the high voltage transformer through the fuse to the primary switch and relay 2. • Turntable rotates. power of microwave oven as POWER LEVEL. (refer to page 1-1) WHEN THE DOOR IS OPENED DURING COOKING • Both the primary switch and relay 2 are cut off
  • LG MB-387W | Service Manual - Page 11
    certified oven unit found to have a microwave emission level in excess of 5 mW/cm2 and should repair any unit found to have excessive emission levels at no cost to the owner and should ascertain the cause of the excessive leakage. The service personnel should instruct the owner not to use the unit
  • LG MB-387W | Service Manual - Page 12
    energy blocking device, record the measured values for future reference. Also enter the information on the service invoice. • The microwave energy leakage should not be more than 4 mW/cm.sq. after determining that all parts are in good condition, functioning properly and genuine replacement
  • LG MB-387W | Service Manual - Page 13
    the load is immediately placed on the center of the turntable which is in the lowest position and the microwave power switched on. • The time T for the temperature of the water to rise by a value earth terminal. CAUTION: DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE SERVICING (refer to page 2-1) 5-3
  • LG MB-387W | Service Manual - Page 14
    oven frame assembly. If the door assembly is not mounted properly, microwaves may leak from the clearance between the door and the oven. Remove and high voltage capacitor. 3) Remove the two screws holding the the suction guide ASS'Y to the oven cavity and remove the high voltage diode earth screw
  • LG MB-387W | Service Manual - Page 15
    be below the limit of 5 mW/cm2. (With a 275 ml. water load). Make sure that gasket is rigidly attached to the magnetron. To prevent microwave leakage, tighten the mounting screws properly, making sure there is no gap between the waveguide and the magnetron. J. REMOVING THE TURNTABLE MOTOR 1) Remove
  • LG MB-387W | Service Manual - Page 16
    activity when the door is opened during cooking and thus to prevent the danger resulting from the microwave leakage. 2) MOUNTING OF THE PRIMARY/MONITOR/ SECONDARY SWITCHES TO THE LATCH BOARD ADJUSTMENT DIRECTION PRIMARY SWITCH MONITOR SWITCH SECONDARY SWITCH 3) INSTALLATION AND ADJUSTMENT
  • LG MB-387W | Service Manual - Page 17
    INTERLOCK CONTINUITY TEST WARNING : FOR CONTINUED PROTECTION AGAINST EXCESSIVE RADIATION EMISSION, REPLACE ONLY WITH IDENTICAL REPLACEMENT PARTS. TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR PRIMARY SWITCH TYPE NO. SZM-V 16-FA-61 OR VP-531A-OF FOR MONITOR SWITCH TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF
  • LG MB-387W | Service Manual - Page 18
    VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE HIGH VOLTAGE TRANSFORMER. (SEE PAGE 2-1) 2. ALL OPERATIONAL CHECKS WITH MICROWAVE ENERGY MUST BE DONE WITH A LOAD (1 LITER OF WATER IN CONTAINER) IN THE OVEN. COMPONENTS HIGH VOLTAGE TRANSFORMER (Wire leads removed) TEST
  • LG MB-387W | Service Manual - Page 19
    COMPONENTS TEST PROCEDURE Antenna Gasket Chassis RESULTS HIGH VOLTAGE CAPACITOR Filament NOTE: When testing the magnetron, be sure to install the magnetron gasket in the correct position and be sure that the gasket is in good condition. Measure the resistance. (Ohm-meter scale: Rx1000) •
  • LG MB-387W | Service Manual - Page 20
    COMPONENTS FUSE TEST PROCEDURE Check for continuity of the fuse with an multi-meter. RESULTS Normal Abnormal H.V. FUSE NOTE: If the fuse is blown, check the primary, the secondary, and the monitor switches, H.V.D. and H.V.C. before replacing the fuse. If the fuse is blown by improper switch
  • LG MB-387W | Service Manual - Page 21
    Normal: A ~ B 40 ~ 60Ω A ~ C 300~500Ω Abnormal: ∞ or several Ω Normal: Approx. 100~200 Ω Abnormal: ∞ or several Ω NOTE : • A MICROWAVE LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR ANY REASON. • MAKE SURE THE WIRE LEADS ARE IN THE CORRECT POSITION. • WHEN REMOVING THE WIRE
  • LG MB-387W | Service Manual - Page 22
    THE COMPLAINT CAREFULLY. IF THE FOLLOWING SYMPTOMS APPLY, PLEASE INSTRUCT THE CUSTOMER IN THE PROPER USE OF THE MICROWAVE OVEN. THIS CAN ELIMINATE AN UNNECESSARY SERVICE CALL. CAUTIONS 1. Check grounding before checking for trouble. 2. Be careful of the high voltage circuit. 3. Discharge the
  • LG MB-387W | Service Manual - Page 23
    PCB assembly. Replace key membrane assembly and check operation. RESULT Continuity. No continuity. Everything works as specified. Still have trouble. CAUSE Defective PCB assembly. Loose connection. Defective key membrane assembly. Defective PCB assembly. REMEDY Replace PCB assembly. Connect them
  • LG MB-387W | Service Manual - Page 24
    (TROUBLE 2) Oven does not operate at all ; Display window does not display any figures and no input is accepted. CONDITION 1. Fuse blows. CHECK Check continuity of
  • LG MB-387W | Service Manual - Page 25
    assembly. Loose connection. Defective fan motor. Defective fan motor. Replace P.C.B assembly. Connection then tightly. Replace fan motor. Replace fan motor. (TROUBLE 4) Oven seems to be operation but little heat is produced in oven load. CONDITION Output is low. CHECK Check the power source
  • LG MB-387W | Service Manual - Page 26
    (TROUBLE 5) No microwave oscillation even though oven lamp and fan motor run (Display operates properly) CONDITION No microwave oscillation. CHECK Disconnect the wire leads from relay 2 and check continuity of relay2. (Operate the unit) RESULT No continuity. Continuity. CAUSE Defective P.C.B
  • LG MB-387W | Service Manual - Page 27
    leads from relay 2 and check continuity relay 2. (Operate the unit) RESULT Abnormal. CAUSE Defective P.C.B. assembly. REMEDY Replace P.C.B. assembly. (TROUBLE 7) Grill CONDITION CHECK 1. Heater is not operating. Heater. RESULT Abnormal. Normal. CAUSE Malfunction the heater. REMEDY Replace
  • LG MB-387W | Service Manual - Page 28
    #EV# EXPLODED VIEW INTRODUCTION MODEL : MB-387W OVEN CAVITY PARTS DOOR PARTS INTERIOR PARTS BASE PLATE PARTS LATCH BOARD PARTS CONTROL PANEL PARTS 6-1
  • LG MB-387W | Service Manual - Page 29
    #EV# DOOR PARTS 13581A 13552A 13536A 13213A 14890A 13720D 14026A 14970A 6-2
  • LG MB-387W | Service Manual - Page 30
    #EV# CONTROL PANEL PARTS 24781S 23572A 249402 250202 268711 WTP004 23790D 249401 250203 250201 6-3
  • LG MB-387W | Service Manual - Page 31
    #EV# OVEN CAVITY PARTS 35264A WTT021 33112U WTT021 948502 WSZ131 33052M WNZ015 35300S WSZ228 36549S 33390G 35889A WTT020 35026G WTP013 6-4
  • LG MB-387W | Service Manual - Page 32
    #EV# LATCH BOARD PARTS 43500A 466001 466003 466001 44510A 6-5 WSZ085
  • LG MB-387W | Service Manual - Page 33
    #EV# INTERIOR PARTS 33808A WTT021 56930V WSZ002 56201B WSZ062 56411A 56324A 34930W WSZ002 55900A 50FZZA 56201A WTT037 56549F 54974S 56912B 50CZZH 948501 56851D WSZ002 54810C 56901A WSZ002 568771 55262A 6-6
  • LG MB-387W | Service Manual - Page 34
    #EV# BASE PLATE PARTS 63303A 56170D WTT021 65006B 63302A WSZ002 6-7
  • LG MB-387W | Service Manual - Page 35
    SCHEMATIC DIAGRAM OF P.C.B 8-1
  • LG MB-387W | Service Manual - Page 36
    PRINTED CIRCUIT BOARD 8-2
  • LG MB-387W | Service Manual - Page 37
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MICROWAVE OVEN
SERVICE MANUAL
MODEL: MB-387W
CAUTION
BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
P/NO : 3828W5S2280
June, 2002
Printed in Korea